The present invention relates to an aerodynamic lift generating device and is an improvement in the lift generating member disclosed and claimed in WO-A-98/07622.
The device of the above-mentioned International application uses a cross-flow or tangential flow rotor positioned in place of the leading edge of a wing-like body and rotating such that the part of the fan rotor at the top of the wing-like body is moving rearwardly, i.e. towards the trailing edge of the wing-like body, whereas the lower part is moving forwardly. The forwardly moving lower part is shrouded and in various of the embodiments of that earlier device the shroud terminates in a lip which helps to form and locate a vortex within the rotor when the rotor is in motion.
Lift control, and hence steering and differential lift generation, in that earlier device was envisaged as being effected by a differential gearbox to drive the parts of the rotor to either side of an aircraft centerline at different rotational speeds so as to generate different lift and thrust values to each side of the centerline.
It is an object of the present invention to provide an alternative means of generating differential lift in such a vehicle.
The present invention envisages using a movable flap as the lip at the leading edge of the shroud defining the undersurface of the wing-like body, so that the lip can be either (i) eliminated by positioning the flap flush with the adjacent part of the shroud or (ii) reduced in its degree of intrusion on the space occupied by the rotor by causing it to adopt a position between the optimum vortex-generating configuration and the fully flush position.
Thus according to a first aspect of the present invention there is provided a lift-generating member comprising:xe2x80x94a wing-like body defining leading and trailing edges and opposed surfaces which converge towards said trailing edge; and a spanwise extending tangential flow rotor positioned adjacent the leading edge of the wing-like body and projecting proud of that one of the opposed surfaces which is uppermost in use of the lift-generating member, whereas the other opposed surface which is the lower one in use of the lift-generating member is defined in part by a shroud which extends forwardly and upwardly and confines the space occupied by the tangential flow rotor and terminates at a lip to define a vortex within the rotor; characterised in that the lip is defined by at least one movable flap which is variable between a first position projecting away from the general direction of the shroud so as to intrude on the space occupied by the rotor and a second position in which it does not intrude to that same extent.
By positioning the flaps to either side of the aircraft centerline in configurations which differ from one another it is possible for the lift at the side where the flap is xe2x80x9cless intrusivexe2x80x9d to be reduced as compared with that where it is xe2x80x9cmore intrusivexe2x80x9d. Because the vortex influences both lift and thrust it is also conceivable to use the differential lift effect to generate also a yawing movement, preferably such that the difference in lift between the two sides of the aircraft centerline and the difference in thrust on the two sides of the aircraft centerline cause the aircraft to execute a slipless banked turn.
The control of the angle of the flaps on both wings simultaneously also enables the lift to be rapidly increased or decreased for manoeuvring, either to effect take off and landing or to manoeuver the aircraft in flight.
It is also possible for the vortex-generating xe2x80x9clipxe2x80x9d to be defined by several different flaps at different regions along the span of the wing, so that the turning effect and/or the banking effect can be more finely tuned by selecting for the lift variations a portion of the flap which is at a greater or lesser distance from the aircraft centerline, thereby changing the moment of the differential lift and thrust forces.